Efficacy and Safety of Reteplase Versus Alteplase in Acute Ischemic Stroke Based on Fibrinogen Levels: The RAISE Trial Subgroup

BACKGROUND: The effects of intravenous thrombolytic agents on fibrinogen differ due to structural differences among the agents. Using data from the RAISE (Reteplase Versus Alteplase for Acute Ischemic Stroke) trial, we aimed to investigate the impact of differences in baseline plasma fibrinogen levels on the efficacy and safety of reteplase versus alteplase within 4.5 hours of acute ischemic stroke symptom onset. METHODS: This post hoc subgroup analysis of the multicenter RAISE trial categorized participants by baseline fibrinogen levels: low (4 g/L). The primary efficacy outcome was excellent functional outcome at 90 days (modified Rankin scale score of 0 or 1). The primary safety outcome was symptomatic intracranial hemorrhage within 36 hours. RESULTS: A total of 1373 patients with acute ischemic stroke were included. Ninety-two in the low fibrinogen group (4 g/L). Adjusted risk ratios of primary efficacy outcome were 1.13 (95% CI, 0.97-1.32) for the low fibrinogen group, 1.13 (95% CI, 1.04-1.23) for the normal fibrinogen group, and 1.09 (95% CI, 0.84-1.42) for the high fibrinogen group. The primary safety outcome showed no difference between reteplase and alteplase in the 3 fibrinogen subgroups. CONCLUSIONS: Among patients with acute ischemic stroke who were treated with either reteplase or alteplase within 4.5 hours after symptom onset, there was no difference observed in the relative efficacy and safety between the 2 groups across the 3 fibrinogen subgroups. However, these findings should be interpreted cautiously and require validation in larger, adequately powered prospective studies. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT05295173.